Product Code:SAE ARP490 Title:Electrohydraulic Servovalves (Cancelled Sep 1993) Issuing Committee:A-6b1 Hydraulic Servo Actuation Committee Scope: Current design and development practices leading to formal liquid rocket engine qualification (USAF) or certification (NASA) will not achieve the specific reliability objectives of future programs. New rocket engine programs are dictating quantified requirements for high reliability in parallel with a cost-constrained procurement environment. These specified reliability levels cannot be validated with the necessary confidence in a timely or cost-effective manner by present methods. Therefore, a new improved process is needed and has been developed. This new reliability certification method will be discussed in detail in the five sections that comprise this document. Primary purposes of this report are to: a. define and illustrate this process; b. point out its strengths and weaknesses; and c. provide guidelines for its application on programs which have specified reliability requirements.ility requirements.